1. Field of the Invention
The present invention relates to a gas purge unit used for a manufacturing process of semiconductors, for example.
2. Description of the Related Art
In the manufacturing process of semiconductors, wafers housed in a wafer transfer container, called such as FOUP and pod, include one where high-density metal wirings or so are formed, for example. It may become impossible to obtain desired characteristics at the time of completion of elements simply because the wafer surface where such high-density metal wirings are formed is slightly oxidized during the process. To prevent foreign material deposition on the wafer surface and oxidation thereof during the process, the transport container is thus necessary to maintain its cleanliness at a high level while controlling oxygen concentration inside of the container.
However, when the wafers in the transport container are brought to various processing apparatuses for performing predetermined processes thereto, a main opening of the container needs to be open for taking the wafers in and out from the container. At this time, the inside of the container is connected through the main opening to the environment in an intermediate chamber with a robot arm that transports the wafers from the container to the various processing apparatuses. The environment in the intermediate chamber is controlled by an apparatus (e.g. EFEM) with fan and filter for purifying the environment in the intermediate chamber to maintain a cleanliness in the chamber at a predetermined value or higher. However, the intermediate chamber may have a cleanliness lower than that in a transport container filled with a cleaning gas, such as nitrogen gas. Thus, when the air in the intermediate chamber intrudes into the transport container, oxygen concentration in the container is increased, and the wafer surface is more likely oxidized.
For example, Patent Document 1 suggests a technique for introducing a purge gas, such as nitrogen gas, into a transport container.
Patent Document 1: Japanese Patent Laid-Open No. 2004-235516